DESCRIPTION: Cell division in the bacterium Caulobacter crescentus produces two different cell types: a motile swarmer cell and a sessile stalked cell. Only the stalked cell is capable of DNA replication and cell division. The long term goal of this project is to understand how cell division and cell differentiation are regulated and coordinated in Caulobacter. Caulobacter is particularly well suited for these studies because it undergoes a relatively simple developmental program with distnct morphologies, and because cell populations can be synchronized easily. The first objective is to define the cell cycle and developmental controls of cell division initiation through an understanding of the factors that control FtsZ. As part of this objective, Dr. Brun plans to explore the mechanism of cell type-specific proteolysis of FtsZ, determine the developmental and temporal control of FtsZ localization, and identify proteins that interact with FtsZ. The second objective is to characterize the regulatory sequences and trans-acting factors responsible for regulation of ftsQA and determine how the transcription of ftsQA is coupled to DNA replication. The final objective is to identify the sigma-54-dependent genes that are required to link pole development to cell division and to define the function of stpA, which appears to be required for proper localization of the stalk and holdfast.